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I’m hoping some of you experienced folks will field the following questions;
1) How confident are you that something can be done to bring the fuel economy up nearer to 12mpg city?
2) What can be done to bring it up?
3) What should I be doing to this truck other than what I have mentioned?
4) Should I be getting a “tuner”? I do not know what the difference is between the AutoEnginuity and something like the Edge tuners. Should I be getting both?
5) Please tell me frankly whether you feel I’ll be successful with the gas mileage I want. If I can’t expect to get 12 city I will sell the truck before doing all this maintenance.
Welcome to the ORG. and the 6.0L Powerstroke. I need a little info about your truck, particularly the axle ratios.
1) I manage around 10-12mpg in town under stock programing a little worse in the winter, that's with a CCLB DRW and 4.30 gears. Your initital 8.9mpg figure is hugely dependent on the towing you did. A lot of it is how you drive, I strive to keep the tach under 2200rpm, and come off the gas to allow the trans to shift. Once a week though, you have to take it out an get at least one WOT run in to keep the turbo and intake healthy.
2) How to bring it up, first is the method of which you drive. Second is to get a free-flowing exhaust on there. (A single 4" Turbo back is all you need with a 3.5" or 4" DP). What tires are you running, size and model will make a difference?
3) Regular maintenance is the key to the 6.0L. You also need to invest in a monitor like the Edge Insight either CS or CTS model, and monitor your coolant and oil temps. This is critical to prevent the oil cooler from destroying your truck. A 15* delta at 65mph on the interstate is the threshold for a coolant flush and oil cooler rebuild. I short cycle oil changes to 6k miles to prevent injector wear, unless you're running synthetic.
4) Tuning, after you get the monitor and see where the truck is sitting. Also, do not go for any tuner that is shift-on-the-fly with the 5R110 transmission. These rely on the transmission re-learn components to adapt to the new powerbands. You will want an SCT tuner, with custom tuning to your trucks strategy and modifications from one of the trusted tuners on this site (PM me for more info on this or anything else 6.0L performance related).
With the SCT tunes, those recalibrate the transmission, are not SOTF, and are very successful here. The higher the HP tune, with a responsible right foot, and you can see as much as a 15% improvement on fuel economy (I have the numbers to prove that).
5) You should be able to reach 12 mpg in the city with a SRW and 3.73 geared truck without any issues, if you maintain and drive the truck accordingly.
Enjoy the new ride.